Glutathione-Independent Prostaglandin: DISCUSSION(1)
In the present study, a major secreted protein was identified in the testicular, epididymal, and seminal fluids of rams and stallions as the glutathione-independent lipocalin-type PGDS (prostaglandin-H2 D-isomerase; (5Z,13E)-(15S)-9a,11 a-epidioxy-15-hydroxyprosta-5,13-dienoate-D-isomerase, EC 188.8.131.52). We identified this compound by microsequencing the protein and by using polyclonal antisera obtained from a peptide deduced from the cDNA sequence of pig PGDS.
This enzyme, which was previously identified in human cerebrospinal fluid as p-trace protein, catalyses the isomerization of prostaglandin (PG) H2 to PGD2, a major primary prostaglandin present in most tissues. This compound has also been detected immunologically in human seminal plasma as p-trace, and it was recently confirmed to be PGDS. This protein has been also detected immunologically in the cauda epididymal fluid and semen of the bull. buy yasmin online
In the present study, the protein was detected by Western blotting in rams and stallions throughout the epididymal tubule. PGDS appeared as a polymorphic and monomeric 22- to 30-kDa molecule with a variable pI range according to the fluid origin and species. The origin of PGDS in the epididymal lumen was mostly related to synthesis and secretion processes by the epithelium of the tubule.